fix: avoid Windows crash while preserving entry metadata

[qartik]

Summary

This PR fixes the Windows CI crash in the isolated test_get_entry_attributes path, scoped separately from the broader QIR 2.0 work in #34.

What Changed

• Avoid generic inkwell function-attribute iteration when finding the entry function.
• Parse QIR bitcode with LLVM bitcode APIs instead of routing bitcode through create_module_from_ir.
• Restore full entry metadata extraction by enumerating all entry-point string attributes via raw LLVM APIs.
• Unify entry attribute extraction so get_string_attrs safely returns all string function attributes again.
• Strip all translated entry-function string attributes after translation, including custom metadata, while still preserving them for get_entry_attributes on input QIR.
• Add a regression test covering custom entry attributes so extraction still works on input and cleanup still happens in translated QIS output.

Notes

#34 overlaps with adjacent code, but it does not fully replace this fix on its own. This branch also updates the bitcode parsing path used by get_entry_attributes, validate_qir, and qir_to_qis, and preserves spec-compatible metadata extraction for output schemas without leaking source entry metadata into translated output.

[Copilot]

Pull request overview

This PR updates the entry-metadata handling path to avoid generic LLVM function attribute iteration, addressing a Windows CI crash (STATUS_ACCESS_VIOLATION) likely originating from LLVM/inkwell FFI behavior.

Changes:

• Switch entry-function detection to a direct lookup for the entry_point string attribute (no attribute iteration).
• Update get_entry_attributes to fetch a fixed set of known QIR entry attributes via direct lookups.
• Remove entry-related attributes during translation by explicitly removing known keys rather than iterating attributes.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

File	Description
src/lib.rs	Replaces attribute iteration with fixed-key lookups for entry metadata extraction and fixed-key removal during translation.
src/convert.rs	Updates find_entry_function to use direct attribute lookup and removes the generic string-attribute iterator helper.

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[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

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[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

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[Copilot]

get_string_attrs always calls LLVMGetAttributesAtIndex even when the attribute count is 0. When count == 0, attrs.as_mut_ptr() comes from an empty Vec and is a dangling non-null pointer; passing it across FFI is risky if LLVM ever dereferences the pointer even when the count is zero. Guard the call (only invoke LLVMGetAttributesAtIndex when count > 0) or pass a null pointer in the zero-count case.